The above discussions have focused primarily on the basic scientific issues underlying the health effects of inhaled and ingested minerals. However, both of these topics can provide solutions to major environmental problems, and they have important ramifications for public policy.
The ``asbestos issue,'' which underlies the first topic discussed above, will likely cost more than $100 billion to remediate in the U.S. alone. Recent evidence supports the notion that chrysotile (which accounts for 90-95% of all asbestos used in the U.S.) poses a much lower risk than amphibole asbestos, and this has led to a call by many scientists to re-evaluate our asbestos policy [ Mossman et al., 1990]. Much of this new evidence resulted from the close collaborations that have developed recently between bioscientists and geoscientists. Had this interdisciplinary approach been implemented at the early stages of asbestos research, it is likely that we would now have a much better understanding of the fundamental scientific issues and, hence, a much improved asbestos policy. Regardless of whether or not geoscience input can help to affect our asbestos policy at this stage, however, it is essential that we continue to develop interdisciplinary research efforts on the other minerals being investigated as potential inhalation hazards (e.g., silica polymorphs and zeolites). This basic research in geosciences can lead to improved risk assessment and to the development of pulmonary-friendly asbestos substitutes. An additional applied outcome of this research might be the ability to predict the toxicity of a mineral without time-consuming and costly in vivo experimentation.
The geoscience research on ``ingested minerals'' is an example of where geoscientists have been successful at providing scientific input to risk assessments. For example, our policies on toxic compounds are concentration based, i.e., a compound is considered toxic when it is present above a specific total concentration. However, when a toxic element is present in a geological material (i.e., mineral), its availability to a biological system is controlled by mineralogical factors such as dissolution characteristics. The study by Borch and coworkers demonstrated this effect in mine tailings containing arsenic. Their data have been incorporated in risk-assessment studies by the California Environmental Protection Agency, and, as a result, they aided a county-level agency in its decision on the fate of a specific occurrence of As-bearing mine tailings [ R. Borch, personal communication]. This is clearly an area ripe for applied geoscience research, for which the ultimate outcome might be a greatly improved method for assessing risks from ingested minerals containing toxic elements.
Geoscientists have a unique opportunity in this emerging interdisciplinary field: we can apply our expertise to a basic research problem---the elucidation of how minerals interact with fluids (an interaction fundamental to many geological problems!)---while we provide critical input to policy issues of national importance.
I thank J. W. Carey, L. Feakes, and several anonymous reviewers for providing constructive reviews of the manuscript, and A. Sorling (Fox Chase Cancer Center) for providing the samples of ferruginous bodies. My time was supported by the Dept. of Energy through a Laboratory Directed Research and Development grant.